The OTDR Subsystem of the TN2000 Optical Cable Monitoring System is an integrated optical fiber monitoring solution that adopts 1U/2U/4U standardized chassis as its hardware carrier. It integrates a monitoring unit RTU consisting of SC, OTDR, OSW, OPD, LSU and other hardware components: the SC enables data interaction with the monitoring center, the OTDR module detects the loss and connection status of optical fiber links, the OSW is built-in with a 64-channel optical switch to realize routing switching and selection for multiple test optical fibers, and the OPD is responsible for monitoring changes in optical power. Specifically designed for DWDM systems and optical cable & fiber monitoring scenarios, the OTDR Subsystem can achieve optical fiber characteristic detection, fault location and resource management throughout the entire process of optical cable construction, maintenance and monitoring. Boasting high adaptability, high detection accuracy, easy operation and maintenance as well as high scalability, it has become a core device for the full-life-cycle management of optical fiber links in optical communication networks. A single set of the OTDR Subsystem can monitor up to 64 optical fiber links simultaneously and be flexibly adapted to the monitoring requirements of star, ring and chain optical fiber networks.